President Pierre Nkurunziza's government has escalated its already intense rhetoric and has warned of resorting to tough measures to stamp out resistance to his recent re-election.

Burundi's most recent violence was triggered by Nkurunziza's successful bid to rescind constitutional term limits and win a third term in office.

In the latest bloodletting, a leading rights activist's son was found dead, the latest in a series of murders linked to the crisis. UN Secretary-General Ban Ki-moon has voiced deep concern over the events.

The United Nations chief also said the discovery of bodies - "many apparently summarily executed" - has become a "regular occurrence" in Burundi's capital Bujumbura.

"The recurring violence and killings in Burundi must stop," he said.

At least 200 people have died in recent violence in Burundi and some 200,000 have fled the country.

The Hague ready to prosecute - if needed

In The Hague, the International Criminal Court warned it was ready to prosecute the instigators of any large-scale violence.

ICC prosecutor Fatou Bensouda said if there is any conduct "whether by security forces, militias or any armed forces" that could "amount to war crimes, crimes against humanity or genocide, no one should doubt my resolve to fulfill my mandate so that the perpetrators do not go unpunished."

Washington's top envoy to the region, Thomas Perriello, specifically condemned what he called the "inflammatory and dangerous government rhetoric."

Perriello will travel to Burundi from Sunday through Wednesday, the State Department said.

"He will communicate the US government's alarm at violence by government and non-government actors inside of Burundi, and the recent dangerous rhetoric by the Burundian government," the State Department said. "He will also call for all parties to exercise maximum restraint and to follow through on commitments to dialogue."

Perriello is also set to discuss the developments with regional leaders in Ethiopia, Rwanda and Uganda.

A history of violence

Burundi itself was wracked by 13 years of conflict between Hutu rebels and the minority Tutsi that left 300,000 dead before a peace deal in 2006.

Its northern neighbor Rwanda is notorious for the 1994 genocide that left at least 800,000 dead.

This week, independent watchdog the International Crisis Group warned that Burundi again faces the "possibility of mass atrocities and civil war."

International alarm has grown over a five-day deadline that expires on Friday for Burundian civilians to hand over weapons or face a new regime crackdown.

The UN Security Council will meet on Monday to discuss the crisis, the French Foreign Ministry said, denouncing the wave of "hate speech" threatening the country.

av/sms (AP, AFP)